RHSA-2007:0964 - Security Advisory

Topic

Updated OpenSSL packages that correct several security issues are now
available for Red Hat Enterprise 5.

This update has been rated as having important security impact by the Red
Hat Security Response Team.

Description

OpenSSL is a toolkit that implements Secure Sockets Layer (SSL v2/v3) and
Transport Layer Security (TLS v1) protocols as well as a full-strength
general purpose cryptography library. Datagram TLS (DTLS) is a protocol
based on TLS that is capable of securing datagram transport (UDP for
instance).

The OpenSSL security team discovered a flaw in DTLS support. An attacker
could create a malicious client or server that could trigger a heap
overflow. This is possibly exploitable to run arbitrary code, but it has
not been verified (CVE-2007-4995). Note that this flaw only affects
applications making use of DTLS. Red Hat does not ship any DTLS client or
server applications in Red Hat Enterprise Linux.

A flaw was found in the SSL_get_shared_ciphers() utility function. An
attacker could send a list of ciphers to an application that used this
function and overrun a buffer with a single byte (CVE-2007-5135). Few
applications make use of this vulnerable function and generally it is used
only when applications are compiled for debugging.

A number of possible side-channel attacks were discovered affecting
OpenSSL. A local attacker could possibly obtain RSA private keys being
used on a system. In practice these attacks would be difficult to perform
outside of a lab environment. This update contains backported patches
designed to mitigate these issues. (CVE-2007-3108).

Users of OpenSSL should upgrade to these updated packages, which contain
backported patches to resolve these issues.

Please note that the fix for the DTLS flaw involved an overhaul of the DTLS
handshake processing which may introduce incompatibilities if a new client
is used with an older server.

After installing this update, users are advised to either restart all
services that use OpenSSL or restart their system.

Solution

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

This update is available via Red Hat Network. To use Red Hat Network,
launch the Red Hat Update Agent with the following command:

up2date

This will start an interactive process that will result in the appropriate
RPMs being upgraded on your system.

Affected Products

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux Workstation 5 x86_64
• Red Hat Enterprise Linux Workstation 5 i386
• Red Hat Enterprise Linux Desktop 5 x86_64
• Red Hat Enterprise Linux Desktop 5 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386

Fixes

• BZ - 245732 - CVE-2007-3108 RSA side-channel attack
• BZ - 309801 - CVE-2007-5135 openssl SSL_get_shared_ciphers() off-by-one
• BZ - 321191 - CVE-2007-4995 openssl dtls out of order vulnerabilitiy

CVEs

• CVE-2007-3108
• CVE-2007-5135
• CVE-2007-4995

References

• http://www.openssl.org/news/secadv_20071012.txt
• http://www.redhat.com/security/updates/classification/#important